Quantification of closed cracks in railway using eddy current pulsed thermography

Rolling contact fatigue cracks are common defects in rail, and they are also the source of various rail defects. When such defects occur, crack closure is caused due to interaction forces between wheels and rails during train running. In this study, eddy current pulsed thermography was applied for quantitative closed crack detection based on the isotherm analysis of temperature distributions. The differences between point-contact crack and opening crack in eddy current and temperature profile were compared in the simulation study. The angle crack test blocks with different closure depths were tested, and the simulation conclusions were consistent with experimental results. Therefore, the proposed method is an effective approach to quantify closed crack.